filling cracks

[sellersrodshop]

i started filling cracks yesterday in preparing for the epoxy-coat. having a heckuva time trying to get this stuff looking right. first, i ended up with the sikaflex "concrete repair" instead of the self levelling. i think most of the trouble lies with the concrete being cold after a couple weeks of sub freezing temps. after 20 yrs experience, i'm kind of a "van gogh" with tube sealers & urethanes & usually am satisfied with the work, but am having a few isues with this. first, if i fill the cracks & run a putty knife over the area, it draws some of the material out of the crack & looks like the acrylic sealer i used under the previous u-coat-it floor coating. the acrylic shrunk over time showing the cracks, thats why i wanted to try a different sealer under this floor. i ended up using the putty knife, but leving the sealer high so the crack will be filled.

went out today & took a razor blade scraper & ran over an area to trim the sealer flush. well, the sealer is stretchy enough that in scraping, it leaves the sealer a little "rough" over the crack or gouges it out a little, not leaving a good smooth surface.

i lightly recoated those areas & i'm gonna give the rest of it another day to set as the floor temps may be causing a slow cure condition. in this pic, you can see the rough spots where the recoat has been applied. i'm hoping the razor scraper will take the second layer off smooth.

any ideas or tips to get this stuff looking correctly?? if there ends up being a small depression, will the epoxy-coat, chips & clearcoat level out & hide the imperfection? also, how important is it to get all of the sealer off of the floor surface around the cracks?? will the razor blade scraper be sufficient or do i need to sand further?? thanks!

 

[LegacyIndustrial]

I recommend you use a product that was designed for this application.
Link: http://legacyindustrial.net/cart/crack-sealant-gel-style-p-206.html

 

[sellersrodshop]

will that epoxy go over what i already have down? there wont be any removing whats already down to apply something else. was hoping to find a new procedure or a quick solution locally as after fooling with this stuff for three days now, my timeframe for getting the floor done is running short. if that 2 part epoxy will go over what i have & you can give me a timeframe on shipping to nashville tn i might give it a try. thanks!

 

[sellersrodshop]

since epoxy-coat says acrylic sealer will be fine, does anyone know if a light skimcoat of that will stick to this sikaflex & allow me to level off the cracks?

 

[LegacyIndustrial]

will that epoxy go over what i already have down? there wont be any removing whats already down to apply something else. was hoping to find a new procedure or a quick solution locally as after fooling with this stuff for three days now, my timeframe for getting the floor done is running short. if that 2 part epoxy will go over what i have & you can give me a timeframe on shipping to nashville tn i might give it a try. thanks!

Well, we apply it over foam backer rod without any issue. If the product in the crack now is compatible with epoxy products it should work.
You need to make sure you get enough in the crack for a bite.

It will take a approx. 2-3 days via UPS Ground to TN.

also...
applying the floor coating over your cracks the way it is now will not solve the problem.

Hope this helps.

 

[sellersrodshop]

thanks scotty!
i think i have solved the problem tonight. seems that a belt sander with a 120 grit belt cuts it down flush with the concrete & leaves a perfect surface. never would have thought that would be the solution as flexible as this stuff is. thought it would end up gouging it out or leaving a "suede" texture but its perfect. thanks again!

 

[jameswood]

thanks scotty!
i think i have solved the problem tonight. seems that a belt sander with a 120 grit belt cuts it down flush with the concrete & leaves a perfect surface. never would have thought that would be the solution as flexible as this stuff is. thought it would end up gouging it out or leaving a "suede" texture but its perfect. thanks again!

That sounds like a good idea you did. Have to take a pic of it.

 

[buening]

Hey man are these expansion or settlement cracks? I second the notion that the source for the cracking needs addressed otherwise they will just reform.

 

[sellersrodshop]

Hey man are these expansion or settlement cracks? I second the notion that the source for the cracking needs addressed otherwise they will just reform.

they are a little of both. the main expansion joint in the center of the floor had opened up a little over time & there were some hairline settling cracks that had popped up not too long after the floor was poured. these have been there for almost 12 yrs with no noticeable changes, so think all will be fine after filling/sanding. the u-coat-it had been down 5 yrs before the fire with acrylic caulk in the cracks & other than the acrylic shrinking where cracks could be seen, the topcoat never cracked or lifted.

 

[rasit]

Not to hijack the thread but the title and

You need to make sure you get enough in the crack for a bite.

got me thinking... does anybody else remember when cracks had hair?

 

[tncatadjuster]

Not to hijack the thread but the title and
got me thinking... does anybody else remember when cracks had hair?

Yes, as a matter of fact I do.

If the epoxy is thin < 25 mils over a soft filler it will crack like crazy.

 

[sellersrodshop]

Not to hijack the thread but the title and
got me thinking... does anybody else remember when cracks had hair?

you can hijack the thread, but you have to post pics as proof

here are the cracks after sanding the filler.

 

[scout57]

you can cut the material as it reacts with a razor blade on a t handle and save your self a ton of griding and a hell of a mess as well as time, don't over fill em and put some #60 silica sand in the bottom to act as a bond breaker just incase ther moving ,( most are drying shrinkage cracks) but heavy point loading can cause them to act as control joints and they may telegraph thru the final coating system, i wouse a flexable epoxy like Euco7oo sika has one can't remember the # it's a good material too..the sika flex is a two part polyurathane ( 227 Spec) not made for cracks but control or expansion joints .

good luck..